6
6 However, it is evident that the relationship is nonlinear. A double-logarithmic specification is ruled out by the negative values of e in the sample and the fact that the relationship clearly does not pass through the origin. EXERCISE 4.5

12
12 Comparing it with the quadratic specification, it does have the advantage of not being downward-sloping for high values of g, but it exhibits excessive sensitivity to g for low values. R 2 is about the same as for the quadratic specification. EXERCISE 4.5

14
14 However R 2 is lower than in the previous specifications. e is systematically underestimated for high values of g and the specification exhibits excessive sensitivity to g for low values. EXERCISE 4.5

15
15 One reason for the poor performance of the hyperbolic function is that it is constrained to be asymptotically tangential to the vertical axis. EXERCISE 4.5

18
18 This specification is compared with the semilogarithmic one. There is very little to choose between them, and indeed the quadratic specification is virtually as good, at least for the data range in the sample. EXERCISE 4.5